Neuroimaging of Primary Progressive Aphasia Variants

Primary progressive aphasia is a neurodegenerative syndrome, with the common feature being aphasia in the absence of marked impairment in other cognitive and behavioral domains. Three primary subtypes have been described: 1) nonfluent or agrammatic primary progressive aphasia, 2) semantic primary progressive aphasia, and 3) logopenic primary progressive aphasia. Although sharing the same primary progressive aphasia designation, these variants show very diverse clinical phenotypes, molecular pathologies, and neuroimaging findings. This review presented current knowledge of clinical phenotypes, molecular pathologies, and multimodal neuroimaging findings, including MR imaging, FDG-PET, amyloid PET, tau PET, and DTI. With increased awareness of the spectrum of neuroimaging abnormalities, the neuroradiologist can potentially add valuable information in correctly categorizing these patients and their underlying pathologies.

Learning Objective: Describe the clinical features and imaging findings that distinguish the variants of primary progressive aphasia.